Now that large, established players — Silver Spring Networks and Cisco (CSCO) — are building out the smart grid network, the next area for innovation will be the applications, software and services designed to run on top of the network. That’s a trend we’ve covered, and it has been heavily discussed at this week’s GreenBeat conference. As Khosla Ventures partner Vinod Khosla put it today, he’s searching for the Twitters and Facebooks of the smart grid.